The two photos above have been taken during ingress in the morning hours, with the Sun still low in the eastern sky, with a small 80/600mm portable refractor from the upper Art's parking lot. The effects of atmospheric turbulence (seeing) are quite obvious. Still, the deliberately overexposed photo of the ingress in progress shows a subtle arc of light along Venus outer edge. This is evidence for the atmosphere of Venus which here refracts the sunlight from behind. The second photo, taken just after ingress was completed, shows the "back drop" effect, mainly caused by image degradation in bad seeing (compare with the photo below at egress, 3rd contact, in better seeing!). A digital camera (Camedia 4040) was used, held behind a 4mm eyepiece and with a total filter factor of about 10,000 to 1, set at 100 ASA, exposure time 1/800 sec.
The above two photos show the progress of Venus' transit during the later morning hours. These are coloured B&W images, taken with a 100mm f/15 refractor, with 3m focal length, on the special ultra-fine-grain, high-contrast film Agfa Ortho 25 (1/2000 sec exposure with special 1:650 front-lens filter).
The image at left is just a much enlarged section around the disk of Venus from the second-last image above. The special film captured remarkable solar surface detail (the Granulation, which are the huge bubbles in the boiling solar surface), hardly visible to the visual observer. Compare with the professional photo of a >10x larger (!) telescope on a mountain site, below (last photo on this page). - Sussex does not do so bad, after all.....
The two photos above where taken during egress just after noon. While contrast then suffered from thin cirrus clouds, the seeing was much better. With the use of a larger (100/1500mm) telescope, a higher resolution was achieved, but the arc of light from the Venus atmosphere is almost lost in the bright background. The same digital camera and filtering was used as above, but with a 10mm eyepiece.
And this is what the powerful Swedish Solar Telescope saw under the clean skies of of the LaPalma Observatory on Roque de los Muchachos, at an elevation of 7300ft. The atmospheric glow at Venus' outer limb is very clearly visible.
Last update: June 16, 2004
Author: Klaus-Peter Schroeder, e-mail to: kps@sussex.ac.uk